It is known, e.g., from U.S. Pat. Nos. 4,116,858 and 4,159,311, that an ion exchange resin may be saturated with aqueous AlCl.sub.3 solution and that reaction with NH.sub.4 OH converts the AlCl.sub.3 in situ to Al(OH).sub.3. This so-formed amorphous Al(OH).sub.3 is then reacted with LiX, where X is halide, at elevated temperature to form crystalline LiX.2Al(OH).sub.3 which is useful in selectively recovering Li.sup.+ values from aqueous solutions, e.g., Li-containing brines.
It is also known, e.g., from U.S. Pat. Nos. 4,116,856 and 4,221,767, that improvements in the above discussed formation of crystalline LiX.2Al(OH).sub.3 are found by reacting amorphous Al(OH).sub.3, or crystalline hydrous alumina (e.g., norstrandite, bayerite, gibbsite or mixtures of these) with LiOH to form LiOH.2Al(OH).sub.3 which is then reacted with LiX to form the crystalline LiX.2Al(OH).sub.3, where X is halide.
Various forms of alumina, Al.sub.2 O.sub.3, are known, some of which occur as natural minerals, some of which are hydrated, and some of which are crystalline. The Handbook of Chemistry shows the following:
______________________________________ Crystalline Name Form M.P. .degree.C. ______________________________________ aluminum oxide, Al.sub.2 O.sub.3 hex. col. 2050 .alpha.-Al.sub.2 O.sub.3, corundum trig;col.cr,n 2015 .gamma.-Al.sub.2 O.sub.3,.gamma.-alumina wh.micro.cr.,n tr.to alpha Al.sub.2 O.sub.3.3H.sub.2 O, gibbsite, monocl.,wh.cr. tr.to Al.sub.2 O.sub.3.H.sub.2 O (hydrargillite) (Boehmite) Al.sub.2 O.sub.3.3H.sub.2 O, bayerite wh.micro.cr. tr.to Al.sub.2 O.sub.3.H.sub.2 O (Boehmite) aluminum oxide, amor.wh.pwd. --xH.sub.2 O,tr. to Al.sub.2 O.sub.3.xH.sub.2 O .gamma.-Al.sub.2 O.sub.3 ______________________________________
Norstrandite is a crystalline hydrous alumina, as are gibbsite and bayerite.
The present process differs from the above previous lithium aluminate preparations in that AlCl.sub.3 is used only once, to provide amorphous Al(OH).sub.3 in a substrate such as a macroporous ion exchange resin. Further loading of Al into the substrate pores is accomplished by crystallizing the alumina in the pores and growing the crystals in an alkaline aluminate solution.